The "direct acting reciprocating steam pump" was invented by Henry R. Worthington
in 1840. It is still used today, often powered by compressed air instead of steam.

DUPLEX PUMPS like the one shown here have two steam and two water cylinders.
Only one of each is shown, the other cylinders being directly behind these.

Duplex pumps have no "dead spots" because one or the other steam piston is always
under force of steam (or compressed air). The two pistons are about 1/4 cycle
out of synchronization with each other.

The steam enters the system through the top chamber on the left where the steam
valve slides back and forth over the various intake and exhaust pipes. The black
hole just under the steam valve is the exhaust vent for used steam.

The back
pump controls the steam valve for the pump shown which controls, through the rocker
arm in the middle, the steam valve for the piston in back.

On the water end
of the pump, on the right here, the lower two valves are the intake valves and
the upper valves are the discharge valves. A hydraulic accumulator is usually
located just above the pump to smooth the flow and prevent water hammer.

As
many as five sets of steam and water cylinders are linked together in various
types of reciprocating steam pumps.

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This
Glossary is a part of a complete educational tutorial about pumps!

Mechanical
pumps are the second most common machine in the world (after electric motors).

Most
people are unfamiliar with how the many different kinds of pumps work!

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